Yes. This is straightforward - You will need to complete the Third Party Authority Form, which grants us authority over the account. This allows Stake to arrange the transfers from your CMA to your US trading account. It also means you can see the balance of that account in Stake.
To complete the form, you only need to fill in Section 1 (with your existing CMA details) and sign section 6.
Once complete, please scan and send to us at email@example.com
As always, feel free to contact us if any issues.